Beware of the Little Guy

In my game, I was having a tough time growing territorially and economically because all of the land in my scenario had been settled. So, I had an idea. I decided to attack my neighbor who also happened to be the weakest and least successful empire up to that point. How hard could it be to conquer them? I couldn't have been more wrong. As soon as I declared war, I was shocked to see that they had a defensive pact with one of the strongest empires, who happened to border me on the other side. Now, I had to battle two empires; one to the north and one to the south. The southern empire that I was now at war with had military units that were very strong and almost equal to the strength of my army. The northern empire that I was at war with had very weak military units that were equal to those that were adaquate many years in the past, but they had lots of units and many extra advantages that are available with experience points. My tanks and armored units were struggling against longbowman and catapults. Even though they are much weaker than my units, every time I tried to attack them, I was at a distinct and large disadvantage. While this was happening, I just kept thinking about the U.S. attacking Iraq. The U.S. has the greatest military and technology in the world, but we are struggling tremendously against people using gorilla warfare tactics and modernly primitive weapons. This disadvantage is mostly because the Iraqis use their background and landscape to their advantage. They attack our units from much higher ground and by surprise. They use little rogue units that in a straight up fight would stand no chance, but due to their advantages, are able to be very successful. Even if they do not win that battle, they prolong the war which does more damage than just winning the battle, both economically and psychologically. So watch out. Just because your neighbor is weaker than you, they could cause you a lot of damage to not just your attacking units but to your empire as a whole.